Influence of buffer layers on the performance of polymer solar cells

The influence of different anode buffer layers on the performance of solar cells based on blends of polyfluorene copolymer poly[2,7-(9,9-dioctyl-fluorene)-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)] (DiO-PFDTBT), acting as electron donor, and [6,6]-phenyl-C61-butyric acid methylester (PCBM), acting as electron acceptor was studied. The buffer layers were constructed from different forms of poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate)(PEDOT-PSS). Variations in open-circuit voltage, short-circuit current, and fill factor were observed. These were attributed to the slight rearrangement of the insulating layer PSS on top of PEDOT, which altered the charge injection at the interface between anode and photoactive layer.